This question has apparently been a make or break factor for many, particularly me. In most cases, I'm put on the razor's edge because of this question. Sometimes, when you say no, you appear undesirable, even if it is your honest answer. Women do know when you're around other women! The other part of this is when a woman asks how many girlfriends have you been with or how many times you've had sex. What could be bad is if that is a low number; which also makes you sexually unattractive. Times you say yes, you may appear to be a player, lonely, or desperate, which can also be a turn-off.